#include<iostream>
#include<queue>
using namespace std;
const int N = 1e6 + 10;
int l[N], r[N];queue<int> q;
void bfs()
{
	q.push(1);
	while (q.size())
	{
		int u = q.front();q.pop();
		cout << u << ' ';
		if (l[u]) q.push(l[u]);
		if (r[u])q.push(r[u]);
	}
}
int main()
{
	int n;cin >> n;
	for (int i = 1; i <= n; i++)
	{
		cin >> l[i] >> r[i];
	}
	bfs();
	return 0;
}